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Several Layers (several + layer)
Selected AbstractsMore Peace for Less Money: Measurement and Accountability in the Swedish Armed ForcesFINANCIAL ACCOUNTABILITY & MANAGEMENT, Issue 4 2005Bino Catasús Studies of measurement and accountability are leading public sector transformation. By examining military work, this paper addresses the relationship between measurements and accountability by highlighting the measurements. Evidence was gathered from documents, political statements and field research. Several layers of accountability systems were found in the organisation. The principal can be the weak link in an accountability relationship if the measurement agenda is in the hands of the agent. The problems seem to go beyond performance and output, and a more fundamental question is challenging the public sector: `Are we doing the right things?' Or an even more dramatic existential question arises: `Why do we exist?' [source] Dynamics of the endoplasmic reticulum during early development of Drosophila melanogasterCYTOSKELETON, Issue 3 2003Yves Bobinnec Abstract In this study, we analyze for the first time endoplasmic reticulum (ER) dynamics and organization during oogenesis and embryonic divisions of Drosophila melanogaster using a Protein Disulfide Isomerase (PDI) GFP chimera protein. An accumulation of ER material into the oocyte takes place during the early steps of oogenesis. The compact organization of ER structures undergoes a transition to an expanded reticular network at fertilization. At the syncytial stage, this network connects to the nuclear envelope as each nucleus divides. Time-lapse confocal microscopy on PDI transgenic embryos allowed us to characterize a rapid redistribution of the ER during the mitotic phases. The ER network is massively recruited to the spindle poles in prophase. During metaphase most of the ER remains concentrated at the spindle poles and shortly thereafter forms several layers of membranes along the ruptured nuclear envelope. Later, during telophase an accumulation of ER material occurs at the spindle equator. We also analyzed the subcellular organization of the ER network at the ultrastructural level, allowing us to corroborate the results from confocal microscopy studies. This dynamic redistribution of ER suggests an unexpected regulatory function for this organelle during mitosis. Cell Motil. Cytoskeleton 54:217,225, 2003. © 2003 Wiley-Liss, Inc. [source] GABAergic projections from the hippocampus to the retrosplenial cortex in the ratEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2007Toshio Miyashita Abstract The retrosplenial cortex (RS) in rats has been implicated in a wide range of behaviors, including spatial navigation and memory. Relevant to this, the RS is closely interconnected with the hippocampus by multiple direct and indirect routes. Here, by injecting the retrograde tracer cholera toxin subunit B conjugated with Alexa488 (CTB-Alexa488) in the granular retrosplenial cortex (GRS), we demonstrate a moderately dense non-pyramidal projection from CA1. Neurons are in several layers, but mainly (about 65%) at the border of the stratum radiatum (SR) and stratum lacunosum moleculare (SLM). In particular, by double-labeling with GAD67 or ,-aminobutyric acid (GABA), we establish that these neurons are GABAergic. Further immunocytochemical screening for calcium-binding proteins, somatostatin (SS) or cholecystokinin (CCK) failed to identify additional neurochemical subgroups; but a small subset (about 14%) is positive for the m2 muscarinic acetylcholine receptor (M2R). Terminations target layer 1 of the GRS, as shown by biotinylated dextran amine (BDA) injections into CA1 and confirmed by a very superficial injection of CTB-Alexa488 in GRS. The superficial injection shows that there is a sparse GABAergic projection from the subiculum to layer 1 of the GRS, in addition to the dense excitatory connections to layer 3. The role of these dual inhibitory,excitatory pathways , within the subiculum, and in parallel from CA1 and the subiculum , remains to be determined, but may be related to synchronized oscillatory activity in the hippocampal complex and GRS, or to the generation of rhythmic activity within the GRS. [source] Depth distribution of earthquakes in the Baikal rift system and its implications for the rheology of the lithosphereGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2001Jacques Déverchčre Summary The correspondence between the predicted brittle,plastic transition within the crust and the maximum depth of earthquakes is examined in the case of the Baikal rift, Siberia. Although little accurate information on depths is available through large- and moderate-size earthquakes, there are frequent indications of foci at 20 km depth and more. We have relocated 632 events recorded at nearby stations that occurred between 1971 and 1997, with depth and epicentral uncertainties less than 5 km, over the eastern and southern parts of the Baikal rift. We have compared these results with other depth distributions obtained in previous studies from background seismicity in the NE rift (1365 events in the Kalar-Chara zone and 704 events in the Muya region). The relative abundance of earthquakes is generally low at depths between 0 and 10 km (7,15 per cent) and high between 15 and 25 km (,50 per cent). Earthquake activity is still significant between 25 and 30 km (9,15 per cent) and persists between 30 and 40 km (7,13 per cent). Very few earthquakes are below the Moho. We use empirical constitutive laws to obtain the yield-stress limits of several layers made of dominant lithologies and to examine whether the observed distribution of earthquakes at depth (519 events controlled by a close station and located within the extensional domain of the Baikal rift system) can match the predicted crustal strength proportion with depth and the deeper brittle,ductile transition in the crust. A good fit is obtained by using a quartz rheology at 0,10 km depth and a diabase rheology at 10,45 km depth with a moderate temperature field which corresponds to a ,100 Myr thermal lithosphere. No dioritic composition of the crust is found necessary. In any case, earthquakes occur at deep crustal levels, where the crust is supposed to be ductile, in a way very similar to what is found in the East African Rift System. From these results we conclude that the seismogenic thickness is ,35,40 km in the Baikal rift system and that the depth distribution of earthquakes is at first order proportional to the strength profile found in a rheologically layered crust dominated by a mafic composition in the ,10,45 km depth range. An upper mantle core with high strength, however, generally prevents it from reaching stress failure at greater depth. [source] Constrained tomography of realistic velocity models in microseismic monitoring using calibration shotsGEOPHYSICAL PROSPECTING, Issue 5 2010T. Bardainne ABSTRACT The knowledge of the velocity model in microseismic jobs is critical to achieving statistically reliable microseismic event locations. The design of microseismic networks and the limited sources for calibration do not allow for a full tomographic inversion. We propose optimizing a priori velocity models using a few active shots and a non-linear inversion, suitable to poorly constrained systems. The considered models can be described by several layers with different P- and S-wave velocities. The velocities may be constant or have 3D gradients; the layer interfaces may be simple dipping planes or more complex 3D surfaces. In this process the P- and S- wave arrival times and polarizations measured on the seismograms constitute the observed data set. They are used to estimate two misfit functions: i) one based on the measurement residuals and ii) one based on the inaccuracy of the source relocation. These two functions are minimized thanks to a simulated annealing scheme, which decreases the risk of converging to a local solution within the velocity model. The case study used to illustrate this methodology highlights the ability of this technique to constrain a velocity model with dipping layers. This was performed by jointly using sixteen perforation shots recorded during a multi-stage fracturing operation from a single string of 3C-receivers. This decreased the location inaccuracies and the residuals by a factor of six. In addition, the retrieved layer dip was consistent with the pseudo-horizontal trajectories of the wells and the background information provided by the customer. Finally, the theoretical position of each calibration shot was contained in the uncertainty domain of the relocation of each shot. In contrast, single-stage inversions provided different velocity models that were neither consistent between each other nor with the well trajectories. This example showed that it is essential to perform a multi-stage inversion to derive a better updated velocity model. [source] A triangular plate element for thermo-elastic analysis of sandwich panels with a functionally graded coreINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 9 2006M. Das Abstract A sandwich construction is commonly composed of a single soft isotropic core with relatively stiff orthotropic face sheets. The stiffness of the core may be functionally graded through the thickness in order to reduce the interfacial shear stresses. In analysing sandwich panels with a functionally gradient core, the three-dimensional conventional finite elements or elements based on the layerwise (zig-zag) theory can be used. Although these elements accurately model a sandwich panel, they are computationally costly when the core is modelled as composed of several layers due to its grading material properties. An alternative to these elements is an element based on a single-layer plate theory in which the weighted-average field variablescapture the panel deformation in the thickness direction. This study presents a new triangular finite element based on {3,2}-order single-layer theory for modelling thick sandwich panels with or without a functionally graded core subjected to thermo-mechanical loading. A hybrid energy functional is employed in the derivation of the element because of a C1 interelement continuity requirement. The variations of temperature and distributed loading acting on the top and bottom surfaces are non-uniform. The temperature also varies arbitrarily through the thickness. Copyright © 2006 John Wiley & Sons, Ltd. [source] A case of necrobiotic xanthogranuloma without paraproteinemia presenting as a solitary tumor on the thighINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 6 2003Sung Eun Chang MD A 82-year-old Korean woman had had a 6-month history of an asymptomatic, flat, hard, red to brown tumor on her right thigh. This lesion had been slowly enlarging with an advancing margin. She had noted gradually developing pain associated with necrosis and ulceration on the lesion. Examination revealed a solitary, 8 × 7.5 cm, yellow to dark red, telangiectatic tumor with multiple areas of punched out ulceration and a peripheral elevated yellowish margin on the right inner upper thigh (Fig. 1). No clinically similar lesions on the periorbital area or other sites were seen. Histologic examination revealed a massive palisading granulomatous infiltration with several layers of extensive bands of necrobiotic zone in the entire dermis and deep subcutaneous tissue (Fig. 2a). In the granulomatous infiltrate in the dermis and subcutis, many various-shaped, some bizarre, angulated, foreign-body type multinucleated giant cells, many Touton giant cells, and a few Langhans giant cells were found to be scattered (Fig. 2b). There were numerous xanthomatized histiocytes. Dense infiltration of lymphoplasma cells was seen in the periphery of the granuloma and perivascularly. Conspicuous granulomatous panniculitis composed of lymphoplasma cells, polymorphonuclear cells, foam cells, and Touton and foreign-body giant cells was also seen. However, cholesterol clefts and lymphoid follicles were not seen. Subcutaneous septae were widened by necrobiotic change and fibrosis with thrombosed large vessels. Gram, Gomeri-methenamine silver and acid-fast stains were negative. The necrobiotic areas were positive to alcian blue. Laboratory investigation revealed elevated white blood cell counts, anemia and elevated erythrocyte sedimentation rate. The following parameters were within the normal range: lipids, glucose, renal and liver function tests, serum complements, serum immunoglobulins, cryoglobulins and antinuclear antibodies. The findings of chest X-ray, skull X-ray and ectorcardiography were normal. Serum electrophoresis and serum immunoelectrophoresis revealed no abnormality. The patient was diagnosed as having necrobiotic xanthogranuloma without paraproteinemia. She was treated with oral steroid (0.5,0.6 mg/kg) and NSAIDS for 1 month with partial improvement of pain and the lesion ceased to enlarge. In the following 1 year of follow-up, with only intermittent NSAIDS, her lesion did not progress and there were no signs of systemic involvement or new skin lesions. Figure Figure 1 . (a) A solitary, red to brown plaque with multiple ulcerations and a peripheral elevated yellowish margin on the inner upper thigh Figure 2. (a) A dermal and subcutaneous massive xanthogranulomatous infiltrate with zonal necrobiosis of collagen (× 20). (b) Prominent infiltrate of xanthomatized histiocytes and giant cells with perivascular lymphoplasma cells (H&E, × 100) [source] The testicular capsule and peritubular tissue of birds: morphometry, histology, ultrastructure and immunohistochemistryJOURNAL OF ANATOMY, Issue 6 2007T. A. Aire Abstract The testicular capsule was studied histologically, morphometrically, ultrastructurally and immunohistochemically in the Japanese quail, domestic fowl, turkey and duck (all members of the Galloanserae). The testicular capsule was, relative to mammals, thin, being 81.5 ± 13.7 µm in the quail, 91.7 ± 6.2 µm in the domestic fowl, 104.5 ± 29.8 µm in the turkey and 91.8 ± 18.9 µm in the duck. The orchido-epididymal border (hilus) of the capsule was much thicker than elsewhere in all birds (from 233.7 ± 50.7 µm in the duck to 550.0 ± 147.3 µm thick in the turkey). The testicular capsule, other than the tunica serosa and tunica vasculosa, comprised, in the main, smooth muscle-like or myoid cells running mainly in one direction, and disposed in one main mass. Peritubular tissue was similarly composed of smooth muscle-like cells disposed in several layers. Actin and desmin intermediate filaments were immunolocalized in the inner cellular layers of the capsule in the quail, domestic fowl and duck, but uniformly in the turkey. Vimentin intermediate filament immunoreaction in the capsule was moderately and uniformly positive in the testicular capsule of only the quail. Actin and desmin, but not vimentin (except very faintly in the turkey) or cytokeratin, were immunolocalized in the peritubular tissue of all birds. The results therefore establish, or complement, some previous observations that these birds have contractile cells in their testicular capsule and peritubular tissue, whose function probably includes the transport of testicular fluid into the excurrent duct system. [source] Ovular development and perisperm formation in Phytolacca americana (Phytolaccaceae) and their systematic significance in CaryophyllalesJOURNAL OF SYSTEMATICS EVOLUTION, Issue 5 2010Hong-Chun ZHENG Abstract,Phytolacca is the biggest and most original genus in Phytolaccaceae and an important genus in plant systematic studies. Light microscopy results show that the Phytolacca americana L. ovule arises from the caulis (floral receptacle). The perisperm and hypostase are simultaneously initiated from the top several layers of cells of chalaza after fertilization, and the perisperm is located between the nucellus and hypostase. In the early stages of development, the hypostase cells are thin-walled with dense cytoplasm, clear nuclei, and some reserve granules. Later, at the heart-shaped embryo stage, the hypostase cells are dead and thick-walled. The main functions of the hypostase may be to maintain cellular division and perisperm growth without delivering nutrient materials to the perisperm. An evolutionary picture of placentation in Caryophyllales is also presented. [source] Role of axon-deprived Schwann cells in perineurial regeneration in the rat sciatic nerveNEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 3 2000M. Popovi The role of Schwann cells (SC) in perineurial regeneration after nerve injury has not yet been resolved. It was hypothesized that SC alone are able to induce at least partial morphological restoration of the destroyed orthotopic perineureum (PN). To test the hypothesis, a permanently denervated segment of the rat sciatic nerve was made acellular by freeze-thawing, except in its most proximal part where non-neuronal cells were left intact. Restoration of the frozen segment by these cells was examined by electron microscopy and immunohistochemistry of the SC marker, S-100 protein, 4 and 8 weeks after injury. The PN regenerated from undifferentiated fibroblast-like cells. In the presence of migrant SC without axons, regenerated cells in the place of the former PN were stacked in several layers and, in accordance with the hypothesis, partially expressed typical features of the perineurial cells (PC): pinocytotic vesicles, short fragments of basal lamina and tight junctions. Migrant SC induced formation of pseudo-minifascicles even in the epineurium. In these, SC organized the adjacent fibroblasts into a multilayered circular sheath, and induced their partial differentiation towards perineurial cells. Further experiments demonstrated that regenerating axons are required for complete morphological differentiation of the regenerated perineurial cells either in the orthotopic PN or in minifascicles. [source] Transcriptional and translational control of C/EBPs: The case for "deep" genetics to understand physiological functionBIOESSAYS, Issue 8 2010Claus Nerlov Abstract The complexity of organisms is not simply determined by the number of their genes, but to a large extent by how gene expression is controlled. In addition to transcriptional regulation, this involves several layers of post-transcriptional control, such as translational repression, microRNA-mediated mRNA degradation and translational inhibition, alternative splicing, and the regulated generation of functionally distinct gene products from a single mRNA through alternative use of translation initiation sites. Much progress has been made in describing the molecular basis for these gene regulatory mechanisms. However, it is now a major challenge to translate this knowledge into deeper understanding of the physiological processes, both normal and pathological, that they govern. Using the C/EBP family of transcription factors as an example, the present review describes recent genetic experiments addressing this general problem and discusses how the physiological importance of newly discovered regulatory mechanisms might be determined. [source] | ||||||||||||||||